Radiant energy collector or reflector

ABSTRACT

A light projector particularly suitable for automobile headlights which will direct a plurality of concentric light beams of different intensities substantially without energy loss. The light projector is provided with a stepped rear reflector of parabolic shape or partially or entirely of the shape of an anamorphosscope. It also is provided with a first front reflector of parabolic shape and a second front reflector disposed inside of the first front reflector of substantially spherical shape. The first front reflector may also be partially or entirely of the shape of an anamorphoscope corresponding to that of the rear reflector. The second front reflector substantially obscures the light source from an observer above a predetermined plane such as a horizontal plane. This will minimize the danger of glare to an approaching driver. On the other hand it will direct substantially all of the light onto the road and permit the beam to reach farther out with the same amount of candle power. The projector may also be used to direct any radiant energy such as electromagnetic waves or sound waves. Additionally it may be used not only to reflect or project radiant energy but also for collecting radiant energy into a focal point.

United States Patent [191 Freeman RADIANT ENERGY COLLECTOR OR REFLECTOR[75] Inventor: Miller L. Freeman, Burbank, Calif.

[73] Assignee: John W. Ervin, Beverly Hills, Calif.

; a part interest [22] Filed: May 21, 1973 [21] Appl. No.: 361,955

[52] U.S. Cl. 313/114, 240/4135 C [51] Int. Cl. H0lk 1/32 [58] Field ofSearch 313/113, 114; 350/301,

350/305, 306; 240/4135 R, 41.35 C, 41.35 D, 41.38 R, 41.38 A

Primary Examiner-Alfred L. Brody Attorney, Agent, or Firm-Edwin A. Oser[111 3,835,342 [451 Sept. 10, 1974 [5 7] ABSTRACT A light projectorparticularly suitable for automobile headlights which will direct aplurality of concentric light beams of different intensitiessubstantially without energy loss. The light projector is provided witha stepped rear reflector of parabolic shape or partially or entirely ofthe shape of an anamorphosscope. it also is provided with a first frontreflector of parabolic shape and a second front reflector disposedinside of the first front reflector of substantially spherical shape.The first front reflector may also be partially or entirely of the shapeof an anamorphoscope corresponding to that of the rear reflector. Thesecond front reflector substantially obscures the light source from anobserver above a predetermined plane such as a horizontal plane. Thiswill minimize the danger of glare to an approaching driver. On the otherhand it will direct substantially all of the light onto the road andpermit the beam to reach farther out with the same amount of candlepower. The projector may also be used to direct any radiant energy suchas electromagnetic waves or sound waves. Additionally it may be used notonly to reflect or project radiant energy but also for-collectingradiant energy into a focal point.

9 Claims, 8 Drawing Figures 7 igvl PATENTED SEP] 01914 sum 1 or 3.

Fig.

RADIANT ENERGY COLLECTOR OR REFLECTOR BACKGROUND OF THE INVENTION Thisinvention relates generally to radiant energy collecting or reflectingsystems and particularly relates to a light beam projector which directsthe light so as to provide a plurality of concentric focused beams withsubstantially no diverging light or substantially without loss ofenergy.

It is well known that light projectors such as automobile headlights maycause considerable glare to practically blind the driver of anapproaching vehicle. It is also known that this may cause accidents.Furthermore, such light projectors are inefficient because the lightenergy that is directed upwards is completely wasted.

Various attempts have been made in the past to minimize the dangercaused by the light beam of a projector being directed in an undesireddirection. Thus, it has been proposed to absorb the light which isnormally directed in an upward direction. As aresult this light energyis transformed into heat. The generation of heat is particularlydetrimental for the sealed beam headlights of a car because the sealedspace of the headlights is not easy to cool.

It is accordingly an object of the invention to provide a lightprojector capable of improving the vision of a driver of a vehicle soequipped and to avoid impairing of the vision of a driver of an oncomingvehicle.

A further object of the present invention is to provide a radiant energyprojector which substantially wastes none of the radiant energy butdirects it into a desired direction such as onto the road and obscuresthe light source from an observer above a predetermined plane.

Another object of the invention is to provide improved apparatus foreither collecting or reflecting radiant energy while minimizing energylosses.

SUMMARY OF THE INVENTION This is accomplished in accordance with thepresent invention by a specially shaped and stepped rear reflector and apair of front reflectors for a radiant energy source such as a lightsource. It will be realized that radiant energy reflectors do not havethe undesirable chromatic aberration which is inherent in any radiantenergy refractors. Since the light reflecting system of the presentinvention does not utilize refractors the apparatus of the presentinvention can be used effectively over the entire electromagentic wavespectrum. Accordingly, it can be used not only for visible light, butinfrared or ultraviolet light as well as other regions of theelectromagnetic spectrum. Furthermore, it may be used for any radiantenergy including, for example, sound energy.

It will also be understood that the apparatus of the present inventionneed not be used only for projecting radiant energy but may be usedequally well for collecting or receiving the radiant energy andconcentrating it into a focal point.

Specifically, the apparatus of the present invention for collecting orreflecting radiant energy includes a first and a second rear reflectorwhich jointly form a stepped reflector. Both of the rear reflectors areof parabolic shape and have a focal point in the energy source or in thepoint where incoming radiant energy is collected. The second rearreflector is disposed between the first rear reflector and the focalpoint.

There are further provided two front reflectors. The first frontreflector is also of substantially parabolic shape having its focalpoint coincident with that of the stepped rear reflector. The firstfront reflector is so positioned and of such a shape as to interceptsubstantially all light which originates from the focal point and wouldotherwise pass through the opening of the first rear reflector. Thesecond front reflector is of substantially spherical shape and forms aportion of the sphere having its origin in the focal point of the otherreflectors. It is so disposed and dimensioned as to interceptsubstantially all energy rays originating from the focal points anddirected through the opening of the first front reflector and above apredetermined plane such as a horizontal plane.

According to a second embodiment the top portion of the first rearreflector and the top portion of the first front reflector may have theshape of an anamorphoscope. According to a second embodiment both thefirst rear reflector and the first front reflector have the shape of ananamorphoscope. This will tend to compress either the top portion orboth top and bottom portions of the resulting light beam and increaseits intensity at the flat edges.

The novel features that are considered characteristic of this inventionare set forth with particularity in the appended claims. The inventionitself, however, both as to its organization and method of operation, aswell as additional objects and advantages thereof, will best beunderstood from the following description when read in connection withthe accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view in perspective of asealed beam lamp suitable for use with an automobile and embodying thepresent invention;

FIG. 2 is a vertical sectional view of a light projector in accordancewith the present invention;

FIG. 3 is a front elevational view of the projector of FIG. 1; I

FIG. 4 is a cross-sectional view of the light beam developed by theprojector of FIGS. 2 and 3;

FIG. 5 is a vertical sectional view of another embodiment of the presentinvention which will provide a light beam having a substantially flattop of high intensity;

FIG. 6 is a front elevational view of the apparatus of FIG. 5;

FIG. 7 is a vertical sectional view of still another embodiment of thepresent invention which provides a light beam having a substantiallyhorizontal top and bottom portion of increased intensity; and

FIG. 8 is a front elevational view of the apparatus of FIG. 7

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawingsand particularly to FIG. 1, there is illustrated by way of example asealed beam headlight lamp 10 for use with an automobile. As explainedbefore, it will be understood that the apparatus of the invention maynot only be used as a projector of light but may be generally used forall forms of radiant energy. Furthermore, it will be understood that itmay not only be used for projecting radiant energy or reflecting it butalso for collecting and receiving the same.

As shown in FIG. 1, the sealed beam lamp is provided with a metallicenvelope 11 and a front window 12 transparent to the light or'in generalto the radiant energy.

Referring now specifically 'to FIGS. 2 and 3, there is illustrated afirst embodiment of the apparatus of the present invention. It includesa first rear reflector l4 and a second rear reflector 15 which jointlyform a stepped rear reflector of parabolic form. Hence the tworeflectors l4 and 15 have a common focal point in which the light sourceor energy source 16 may be located. The second rear reflector 15 isdisposed between the first rear reflector 14 and the light source 16.Its opening is defined by a plane 17 which is spaced from the lightsource 16 and intersects the common axis of the two rear reflectors l4and 15 and the light source 16 at right angles.

The light projector of FIGS. 2 and 3 is also provided with a frontreflector 20 which may also be of parabolic shape and have its focalpoint in the light source 16. It is spaced from the light source 16 sothat its rear opening is defined by a plane 21 parallel to and spacedfrom the plane 17. The front reflector 20 is so dimensioned and sodisposed as to intercept substantially all of the light rays from thelight source 16 which would otherwise pass through the opening of therear reflector 14.

In case of anautomobile sealed beam headlamp the opening of the rearreflector 14 may be closed by a window 12 of transparent material, thatis transparent to the energy of the source 16.

It is still possible that light rays from the light source 16 may passthrough the opening of the first front reflector 20 in an upwarddirection. This is prevented by the provision of the second frontreflector 23.

The second front reflector 23 is of spherical shape and has its originin the light source 16. its lower portion is horizontally cut off asclearly shown at 24 in FIG. 3. Accordingly, it will obscure the lightsource 16 from an observer standing above a horizontal plane defined bythe intersection of the lower edge 24 of the second front reflector 23and the tight source 16. The operation of the light projector of FIGS. 2and 3 will now be explained.

A light ray such as shown at 25 is reflected by the first rear reflector14 and emerges as a focused light beam. Similarly, a light ray such asshown at 26 which is directed toward the first front reflector 20 isreflected thereby and issues as a horizontal light ray to provide asecond focused beam. This is due to the fact that any light beamoriginating from the focal point of a paraboloid will issue as a focusedor parallel light beam.

As explained before, the front reflector 20 is so disposed and arrangedto intercept light rays such as 26 which otherwise would issue throughthe opening of rear reflector 11. Additional light rays from the lightsource 16 which are intercepted by the second rear reflector 15 alsoissue as a central collimated light beam.

However, this would still make it possible for a light beam such asshown at 28 to pass through the opening of front reflector 20 in anupward direction. These light rays are reflected by the second frontreflector 23 through the light source 16 onto the second rear reflector15 to emerge as a light ray 30 in a parallel direction.

Accordingly, the light source is obscured from any observer standingabove a horizontal plane defined by the lower edge 24 of the secondfront reflector 23.

The various elements, that is the second rear reflector 15, the frontreflector 20 and the second front reflector 23 may be secured to eachother and either to the window 12 or to the first rear reflector 14 inany conventional manner. Preferably. the reflectors are sccured bynon-reflecting elements. For example, the various reflectors may besecured in the manner illustrated in FIG. 8 of the US. Pat. to LessmanNo. 3,038,372 or as illustrated in FIG. 1 of the US. Pat. to BenjaminNo. 1,880,399. Alternatively, the construction shown in FIG. 2 of theUS. Pat. to Irujo No. 2,084,245 may be used. However, for the sake ofclarity, these connections have not been shown in the drawings.

As shown particularly in FIG. 4, there will now be created a focusedring-shaped or annular outer light beam 32 corresponding to thering-shaped area be tween the flrst rear reflector 14 and the firstfront reflector 20. A second concentric light beam 33, which is alsoring shaped, is defined by the ring-shaped area between the frontreflector 20 and the second rear reflector 15. Finally, the centrallight beam 34 of circular cross section corresponds to the lightreflected by the second rear reflector 15. This light beam will besomewhat more intense than the light beam 33 because its intensity isincreased by the light reflected by the second front reflector 23. Thesemi-circular area 35 corre sponds to the shadow of the second frontreflector 23. Besides the three focused light beams 32, 33 and 34, therewill be a small amount of divergent light which passes from the lightsource 16 through the lower portion of the opening of the first frontreflector 20. This additional light further illuminates the road.

Referring now to FIGS. 5 and 6, there is illustrated another embodimentof the present invention which serves the purpose to further compressthe top of the light beam. To this end the upper portion 38 of the firstrear reflector 14 is made in the shape of an anamorphoscope. Areflecting anamorphoscope is the equivalent of a cylinder lens and hasthe property of compressing the light in a predetermined plane. Thus,the first rear reflector 14 is asymmetrical in shape and has a lowerportion in the shape of a paraboloid and the upper portion 38 in theshape of an anamorphoscope. The envelope or housing 11 may retain itsconventional parabolic shape so that the projector of the invention maybe readily installed in a conventional envelope or housing.

The upper portion 40 of the second rear reflector 15 also has the sameshape, that is the shape of an anamorphoscope. The same applies to theupper portion 41 of the first front reflector 20. As clearly shown inFIG. 6, the three reflectors 38, 40 and 41 each have a flattopped upperportion. It will therefore be realized that the corresponding lightbeams such as 32, 33 and 34 as shown in FIG. 4 will also each have aflat top portion. Due to the fact that the light has been compressed,these top portions are more intense than the remainder of the beams.

As a result the light beam will reach farther ahead of a car soequipped.

Referring now to FIGS. 7 and 8, there is illustrated still anotherembodiment of the present invention. The light projector of FIGS. 7 and8 generates a light beam which has essentially flat top and bottomportions which are more intense than the remainder of the light beam.This is accomplished by forming the first rear reflector 14 with both atop portion 38 and a bottom portion 42 in the shape of ananamorphoscope. In other words the entire first rear reflector 14 hasthe shape of an anamorphoscope. The same is true of the second rearreflector 15 where both the top portion 40 and the bottom portion 43have the shape of an anamorphoscope. Finally, the first front reflectoralso has not only a top portion 41, but a bottom portion 44 of the shapeof an anamorphoscope. Thus to, summarize, both rear reflectors 14 and 15and the front reflector 20 have the shape of an anamorphoscope with acommon focal point in the light source 16. As a result, it will berealized that the three light beams such as shown at 32 to 34 in FIG. 4will all have substantially flat top and bottom portions of increasedintensity.

It may be pointed out that the transparent window 12 may be omittedexcept in the case of the sealed beam lamp of a car. Also, the lightsource 16 need not necessarily be a point-like light source as shownschematically in the drawings, but may be of extended form. It may, forexample, consist of a single filament or of a double filament such asare used in some automobile sealed beam lamps to provide both the highand low beam in a single lamp structure.

The various reflectors of the light projector of the invention may bemanufactured in any suitable manner. For example, they may be molded,forged, stamped, welded machined or electroformed. Suitably, thereflectors may be formed on a mold from a suitable plastic materialwhich may subsequently be coated with a light reflecting material such,for example, as aluminum. It will be understood that other materialssuch as safety glass, metal, plastic, or ceramic may be used for theapparatus of the invention.

There has thus been disclosed apparatus for collecting or reflectingradiant energy. Specifically, the apparatus may be used as a lightprojector. It may be so designed that no light can escape in an upwarddirection above a predetermined plane to minimize glare. This of coursewill obscure the light source from an observer above a predeterminedplane. Nevertheless, substantially no light is lost but all light issimply redirected into a desired direction. The resulting light beam maybe caused to have three concentric portions which may be made to haveeither a flat top or a flat bottom or both flat top and bottom portions.These flat portions are of increased light intensity due to the factthat they are created by a reflector in the shape of an anamosphoscopewhich tends to compress the light. This helps to direct the light beamfurther ahead with the same amount of candle power which is presentlylimited in the case of cars. Since the light projector used onlyreflecting elements, there is no chromatic aberration. It will berealized that the greater portion of the energy is reflected only oncein a solid angle from the source into the desired beam. Only the smallportion of the light collected by the second'front reflector isreflected twice.

What is claimed is:

1. A radiant energy collecting or reflecting system for collecting orreflecting radiant energy from or into a predetermined area, said systemcomprising:

a. a first rear reflector of substantially parabolic shape, said firstrear reflector having a focal point toward which to direct incomingradiant energy or from which to direct radiant energy outwardly;-

b. a second rear reflector of substantially parabolic shape disposedbetween said focal point and said first rear reflector, said second rearreflector having a focal point substantially coinciding withv that ofsaid first rear reflector whereby said rear reflcctors jointly form astepped reflector;

c. a first front reflector of substantially parabolic shape having itsfocal point substantially coinciding with that of said rear reflectors,said first front rcflector being apertured to pass light thercthroughand being disposed for intercepting substantially all energy rays whichwould originate from said focal point and pass through the opening ofsaid first rear reflector; and

d. a second front reflector of substantially spherical shape forming aportion of a sphere having its origin substantially coinciding with saidfocal points, said second front reflector being so disposed as tointercept all rays originating from said focal points anddirected'through the opening of said first front reflector and above apredetermined plane.

2. A reflecting system as defined in claim 1 wherein correspondingportions of said first and second rear reflectors are substantiallyanamorphic reflectors, and wherein the corresponding portion of saidfirst front reflector is a substantially anamorphic reflector.

3. A reflecting system as defined in claim 1 wherein said first andsecond rear reflectors and said first front reflector are substantiallyanamorphic reflectors.

4. A radiant energy reflecting system for directing radiant energy inpredetermined directions, said system comprising:

a. a radiant energy source;

b. a first rear reflector of substantially parabolic shape having itsfocal point substantially in said energy source;

0. a second rear reflector of substantially parabolic shape providingwith said first rear reflector a stepped reflector and having its focalpoint substantially in said energy source, said second rear reflectorbeing disposed between said first reflector and said energy source;

d. a first front reflector of substantially parabolic shape disposedahead of said energy source and having a focal point substantially insaid energy source, said first front reflector being disposed tointercept substantially all rays which would otherwise pass through theopening of said first rear reflector, said first and second rearreflectors and said first front reflector having openings disposed insubstantially parallel planes; and

e. a second front reflector of substantially spherical shape having itsorigin substantially in said energy source, said second front reflectorbeing disposed within said first front reflector so as to interceptsubstantially all energy rays which would otherwise pass above apredetermined horizontal plane, whereby said reflecting system willproject three concentric light beams of substantially circular shapewith substantially no energy being directed above said predeterminedhorizontal plane.

5. A reflecting system as defined in claim 4 wherein the opening of saidfirst rear reflector and of said first front reflector is closed by awindow of a material transparent to the radiant energy.

A radiant energy reflecting system for directing radiant energy inpredetermined directions, said system comprising:

the

a first front reflector having an upper substantially anamorphicreflector portion and a lower portion of substantially parabolic shapedisposed ahead of said energy source and having a focal pointsubstantially in said energy source, said first front reflector beingdisposed to intercept substantially all rays which would otherwise passthrough the opening of said first rear reflector, said first and secondrear reflectors and said first front reflector having openings disposedin substantially parallel planes; and

. a second front reflector of substantially spherical shape having itsorigin substantially in said energy source, said second from reflectorbeing disposed within said first front reflector so as to interceptsubstantially all energy rays which would otherwise pass above apredetermined horizontal plane, whereby said reflecting system willproject three concentric light beams with substantially no energy beingdirected above said predetermined horizontal plane.

A reflecting system as defined in claim 6 wherein opening of said firstrear reflector and of said first front reflector is closed by a windowof a material transparent to the radiant energy.

8. A radiant energy reflecting system for directing radiant energy inpredetermined directions, said system comprising:

a. a radiant energy source;

b. a first substantially anamorphic rear reflector having its focalpoint substantially in said energy source;

0. a second substantially anamorphic rear reflector providing with saidfirst rear reflector a stepped reflector and having its focal pointsubstantially in said energy source, said second rear reflector beingdisposed between said first reflector and said energy source;

d. a first substantially anamorphic front reflector disposed ahead ofsaid energy source and having a focal point substantially in said energysource, said first front reflector being disposed to interceptsubstantially all rays which would otherwise pass through the opening ofsaid first rear reflector, said first and second rear reflectors andsaid first front reflector having opening disposed in substantiallyparallel planes; and

. a second front reflector of substantially spherical shape having itsorigin substantially in said energy source, said second front reflectorbeing disposed within said first front reflector so as to interceptsubstantially all energy rays which would otherwise pass above apredetermined horizontal plane, whereby said reflector system willproject three concentric light beams with substantially no energy beingdirected above said predetermined horizontal plane,

9. A reflecting system as defined in claim 8 wherein the opening of saidfirst rear reflector and of said first front reflector is closed by awindow of a material transparent to the radiant energy.

1. A radiant energy collecting or reflecting system for collecting or reflecting radiant energy from or into a predetermined area, said system comprising: a. a first rear reflector of substantially parabolic shape, said first rear reflector having a focal point toward which to direct incoming radiant energy or from which to direct radiant energy outwardly; b. a second rear reflector of substantially parabolic shape disposed between said focal point and said first rear reflector, said second rear reflector having a focal point substantially coinciding with that of said first rear reflector whereby said rear reflectors jointly form a stepped reflector; c. a first front reflector of substantially parabolic shape having its focal point substantially coinciding with that of said rear reflectors, said first front reflector being apertured to pass light therethrough and being disposed for intercepting substantially all energy rays which would originate from said focal point and pass through the opening of said first rear reflector; and d. a second front reflector of substantially spherical shape forming a portion of a sphere having its origin substantially coinciding with said focal points, said second front reflector being so disposed as to intercept all rays originating from said focal points and directed through the opening of said first front reflector and above a predetermined plane.
 2. A reflecting system as defined in claim 1 wherein corresponding portions of said first and second rear reflectors are substantially anamorphic refleCtors, and wherein the corresponding portion of said first front reflector is a substantially anamorphic reflector.
 3. A reflecting system as defined in claim 1 wherein said first and second rear reflectors and said first front reflector are substantially anamorphic reflectors.
 4. A radiant energy reflecting system for directing radiant energy in predetermined directions, said system comprising: a. a radiant energy source; b. a first rear reflector of substantially parabolic shape having its focal point substantially in said energy source; c. a second rear reflector of substantially parabolic shape providing with said first rear reflector a stepped reflector and having its focal point substantially in said energy source, said second rear reflector being disposed between said first reflector and said energy source; d. a first front reflector of substantially parabolic shape disposed ahead of said energy source and having a focal point substantially in said energy source, said first front reflector being disposed to intercept substantially all rays which would otherwise pass through the opening of said first rear reflector, said first and second rear reflectors and said first front reflector having openings disposed in substantially parallel planes; and e. a second front reflector of substantially spherical shape having its origin substantially in said energy source, said second front reflector being disposed within said first front reflector so as to intercept substantially all energy rays which would otherwise pass above a predetermined horizontal plane, whereby said reflecting system will project three concentric light beams of substantially circular shape with substantially no energy being directed above said predetermined horizontal plane.
 5. A reflecting system as defined in claim 4 wherein the opening of said first rear reflector and of said first front reflector is closed by a window of a material transparent to the radiant energy.
 6. A radiant energy reflecting system for directing radiant energy in predetermined directions, said system comprising: a. a radiant energy source; b. a first rear reflector having an upper substantially anamorphic reflector portion and a lower portion of substantially parabolic shape having its focal point substantially in said energy source; c. a second rear reflector having an upper substantially anamorphic reflector portion and a lower portion of substantially parabolic shape providing with said first rear reflector a stepped reflector and having its focal point substantially in said energy source, said second rear reflector being disposed between said first reflector and said energy source; d. a first front reflector having an upper substantially anamorphic reflector portion and a lower portion of substantially parabolic shape disposed ahead of said energy source and having a focal point substantially in said energy source, said first front reflector being disposed to intercept substantially all rays which would otherwise pass through the opening of said first rear reflector, said first and second rear reflectors and said first front reflector having openings disposed in substantially parallel planes; and e. a second front reflector of substantially spherical shape having its origin substantially in said energy source, said second front reflector being disposed within said first front reflector so as to intercept substantially all energy rays which would otherwise pass above a predetermined horizontal plane, whereby said reflecting system will project three concentric light beams with substantially no energy being directed above said predetermined horizontal plane.
 7. A reflecting system as defined in claim 6 wherein the opening of said first rear reflector and of said first front reflector is closed by a window of a material transparent to the radiant energy.
 8. A radiant energy reflecting system for directing radiant energy in predetermined directions, sAid system comprising: a. a radiant energy source; b. a first substantially anamorphic rear reflector having its focal point substantially in said energy source; c. a second substantially anamorphic rear reflector providing with said first rear reflector a stepped reflector and having its focal point substantially in said energy source, said second rear reflector being disposed between said first reflector and said energy source; d. a first substantially anamorphic front reflector disposed ahead of said energy source and having a focal point substantially in said energy source, said first front reflector being disposed to intercept substantially all rays which would otherwise pass through the opening of said first rear reflector, said first and second rear reflectors and said first front reflector having opening disposed in substantially parallel planes; and e. a second front reflector of substantially spherical shape having its origin substantially in said energy source, said second front reflector being disposed within said first front reflector so as to intercept substantially all energy rays which would otherwise pass above a predetermined horizontal plane, whereby said reflector system will project three concentric light beams with substantially no energy being directed above said predetermined horizontal plane.
 9. A reflecting system as defined in claim 8 wherein the opening of said first rear reflector and of said first front reflector is closed by a window of a material transparent to the radiant energy. 